Description: (Applicant's Description) SPECIFIC AIMS 1. To continue core facilities for uniform tissue processing, embedding, cutting, routine staining and immunohistochemical staining. 2. To analyze experimental nervous system tumors and surrounding brain tissues for histopathological, immunopathological and molecular genetic parameters. 3. To characterize human nervous system tumors by standard neuropathological, immunohistochemical and molecular genetic classification criteria.